More than 1,000 people were feared dead and authorities warned a meltdown may be under way at a nuclear plant after a monster tsunami devastated a swathe of northeast Japan.

Reactor cooling systems failed at two generating plants after Friday’s record 8.9-magnitude earthquake hit, unleashing a terrifying 10-metre (33-foot) high wave that tore through coastal towns and cities, destroying all in its path.

Radiation 1,000 times above normal was detected in the control room of one nuclear plant, although authorities said levels outside the facility’s gates were only eight times above normal, spelling “no immediate health hazard.”

But officials warned one of the plants, just 250 kilometres northeast of Tokyo, “may be experiencing nuclear meltdown,” Kyodo and Jiji reported.

Tens of thousands of people were evacuated from around the plants as Tokyo Electric Power, which runs the facilities, said it had released some radioactive vapour at both locations to relieve building reactor pressure.

“We are not in a situation in which residents face health damage,” Chief Cabinet Secretary Yukio Edano told reporters, according to Jiji news agency.

The two nuclear plants affected are the Fukushima No. 1 and No. 2 plants, both located about 250 kilometres (160 miles) northeast of Tokyo.

The WSJ confirms that people within a six-mile (i.e. 10-kilometer) radius were already being shipped out hours ago. Also, an update on the control room, where radiation levels reached 1,000 times the normal rate earlier:

Radiation levels aren’t supposed to rise in a control room, which is designed to allow operators to continue working during emergencies and is equipped with filtration systems and other design features to protect workers from radiation exposure. Nevertheless, experts said that a level that is 1,000 times normal probably isn’t immediately harmful.

The technicians on the scene battling this thing must be signing years of their lives away, if not decades.